"We are deeply sorry for all the families," Cohava Eyal, Ramon's sister, told The Associated Press at Bush Intercontinental Airport.

Eyal, wearing a space shuttle mission pin, was among six family members and three friends arriving in Houston.

"We are wrapped up in our grief now," said family friend Hudit Keren.

Ramon, a former Israeli fighter pilot, had four children, ages 5 to 15.

Daniel Ayalon, the Israeli ambassador to United States, arrived in Houston on Sunday to meet with NASA officials for an update on the search of remains.

Under Jewish law, mourners must bury their dead within 24 hours, then immediately begin observing a ritual called sitting shiva - seven days during which mourners are expected to stay at home, greet visitors and pray.

However, it is unclear whether any of Ramon's remains will be found, which means his family must consult with a rabbi about how to proceed.

Practices vary among branches of Judaism and rabbis have some discretion in individual cases. The same problem came up after Sept. 11, when few full bodies were recovered in the World Trade Center rubble.

Jewish law requires direct evidence, normally the body itself, to confirm a death. In Ramon's case, the disintegration of the shuttle should be evidence enough to allow the family to hold a memorial service and begin sitting shiva immediately, said Rabbi Kassel Abelson, chairman of the Committee on Jewish Law and Standards for the Conservative movement.

If some body parts are found later, the family will be directed to bury the remains and sit shiva until sundown of that day, he said.

Ambassador Ayalon said he met Saturday night with Ramon's widow, Rona. He said Rona Ramon "knew he died very happy. This was the height of his career."

Asked if this gave him pause about the U.S. space program, he said: "No, not at all. This event has galvanized the two countries together. We have full trust in NASA."